Add synced lyrics display with LrcLib

[guitaripod]

Summary

Strawberry already fetches lyrics from LrcLib, but discards the syncedLyrics field and only uses plainLyrics. This PR threads time-synced LRC data through the entire lyrics pipeline and displays it as a real-time scrolling view in the context panel.

Screencast_20260405_093914.mp4

• LrcLib provider now extracts and parses the syncedLyrics JSON field that was previously ignored
• New LrcParser utility parses [MM:SS.CC] LRC timestamps into structured LyricLine objects
• New SyncedLyricsWidget (QListWidget subclass) displays lyrics line-by-line with:
  • Smooth pixel-level animated scrolling (QPropertyAnimation + ScrollPerPixel)
  • Current line highlighted in bold with full opacity
  • Distance-based fade effect — lines farther from current gradually dim
  • Click any line to seek playback to that timestamp
  • Auto-scroll pauses for 3 seconds when user scrolls manually
• ContextView gets a 250ms position sync timer that polls the engine and updates the lyrics widget
• Falls back gracefully to the existing plain text display when synced lyrics aren't available
• All other lyrics providers continue to work unchanged

Setup

To see synced lyrics, LrcLib must be enabled in your lyrics provider settings:

1. Go to Tools → Settings → Lyrics
2. Check the LrcLib checkbox to enable it
3. Optionally drag LrcLib to the top of the list for priority
4. Click OK and play a track

LrcLib has excellent coverage for popular music. If a track has synced lyrics available on lrclib.net, they will display automatically. Otherwise, plain text lyrics from other providers are shown as before.

New files

File	Purpose
src/lyrics/lyricline.h	LyricLine struct (timestamp + text) and SyncedLyrics type
src/lyrics/lrcparser.h/.cpp	LRC format timestamp parser
src/context/syncedlyricswidget.h/.cpp	Synced lyrics display widget

Modified files

File	Change
lyricssearchresult.h	Added synced_lyrics field
lrcliblyricsprovider.cpp	Extracts syncedLyrics from API response
lyricsfetchersearch.h/.cpp	Threads synced lyrics through signals, +0.5 score bonus
lyricsfetcher.h/.cpp	Threads synced lyrics through signals
contextview.h/.cpp	Integrates widget, position timer, Player reference
mainwindow.cpp	Passes player to ContextView, connects Paused/Resumed/Seeked signals
CMakeLists.txt	Registers new source and header files

[jonaski]

This is great, but needs to be optional. Also, when testing here there is a huge gap between the album cover and the lyrics: